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Re: Re-finishing flat ways

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  • stevenhkb
    I had a Atlas 42 bed done by a competent grinder shop many years ago, cost an arm and a leg tho, got a decent job. He did top and sides only. You are right
    Message 1 of 6 , Mar 1, 2002
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      I had a Atlas 42" bed done by a competent grinder shop many years
      ago, cost an arm and a leg tho, got a decent job. He did top and
      sides only.

      You are right about fixturing to avoid changes when the mag is turned
      off, my shop would not do the underside of the rails because he was
      afraid of having to true up his wheel too much to achieve a "Square"
      edge. He didn't realize it did not have to be that square. I hand
      scraped it to relieve binding at the end of the bed on the
      underside. Long and tiresome job. I think you handle the change in
      dimensions by removeing shimms somewhere to keep the shaft in the
      center of the half-nuts. Not sure about this.
      Steve

      >
      > John Been watching this thread on getting a bed reground. I
      > would think twice about sending lathe to auto machine shop. The
      > type of grinding equipment in machine shops is geared so as most
      > operations are idiot proof. I do not mean to say that all shops are
      > like this . What i mean is that valve grinders, head resurfacers,
      and
      > such are made so that the operator has only to put the head in and
      > take off enough to clean up. Where as a lathe bed can have wear
      most
      > likely where the carraige was running.( or twisted) So, if I was
      > grinding it I would go to a real grinding shop and tell them you
      want
      > it ground first with the flat side down and shimed where the bed
      has
      > been worn( where the carriage was running)If this is not done the
      > electro megnet will pull the bed down aND WHEN IT IS RELEASED IT
      WILL
      > SPRING OUTWARD.After the bottom side is done I would tell them to
      > dust the flat side to clean up. You could mic the width, if it is
      > only a couply thou I might be inclined to let it go . To grind the
      > edges requires the grinder hand to clamp the bed against a couple
      of
      > larage angle plates. Again you are at his mercy, be cause he will
      > have to indicate the inside rail surfaces parrall . You might also
      > mic the rails seperately micing under the head stock and at the
      > endsas the tail stock rode on the inside.You can mike the edge
      > thickness after he completes the top. If you want the bottom edge
      > ground it will be another setup( more money)I would not do this
      > unles s it was really worn. As far as price 75$ ought to be far
      about
      > i hr.for top and bottom
      > Almost retired grinder hand
      > Chris Miller
    • LouD31M066@aol.com
      Yeah I got one or two. 1) Engine blocks and heads warp considerable so auto machine shop work can involve removing significant thickness of metal whereas all
      Message 2 of 6 , Mar 1, 2002
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        Yeah I got one or two. 1) Engine blocks and heads warp considerable so auto
        machine shop work can involve removing significant thickness of metal whereas
        all you may need with lathe bed is to even up lathe bed wear by accurately
        removing 0.001 or possible a tad more. 2) A surface acceptable to mechanic
        may be flat
        to plus or minus 0.001 or even more under a straight edge whereas a surface
        needed for a true lathe bed my be plus or minus 0.0000 or as close as you can
        get.
        The standards of acceptable accuracy between machine tool and products made
        by a machine tool are all downhill. That is a machine can not produce parts
        to a higher level of precision than the machine and usually somewhat less.
        I think you should have a heart to heart to talk with person who is doing the
        work
        and discuss whether his machine and standards of precision will result in an
        improved machine or not. Anyway there is my $0.000000002 worth.
        Louis


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